It has been conventional to interconnect a tubular conduit within the passage of a second conduit, often referred to as a housing, by inserting a leading end of the tubular conduit axially through an entry opening into the housing passage. The latter may comprise an axially extending series of stepped bores or interconnecting passages of different diameters including an enlarged diameter passage connecting the entry opening with a reduced diameter passage. The tubular conduit in such an assembly is provided with an annular external radial projection or enlargement that partitions the conduit into leading and trailing portions and is dimensioned to pass through the entry into the enlarged diameter passage, but to prevent insertion into the reduced diameter passage.
Suitable sealing means may be provided within the reduced diameter passage to effect an annular seal between the housing and leading portion of the conduit. A bushing within the reduced diameter passage extends around the leading portion of the conduit between the radial enlargement and the sealing means to hold the latter in position. A retainer within the enlarged diameter passage has resilient portions that yield to enable insertion of the conduit and its enlargement into the housing passage, but at the assembled position engage portions of the housing and conduit enlargement to prevent removal of the conduit and to effect an efficient fluid tight coupling.
Many retainers have been designed heretofore, some molded from flexible plastic and others formed from resilient metals, such as sheet spring steel, but all such retainers have been subject to objections. For example, the plastic retainers lack compactness and are unsatisfactory for use in couplings demanding strength or subject to high temperature. In some applications, the pressure tending to force the conduit axially out of the housing passage can amount to several hundred pounds. In consequence, conventional couplings are subject to excessive shearing or buckling when formed from resilient plastics, or even spring steel if not properly constructed.
Couplings of the type described are frequently employed in corrosive environments, as for example when used with an automobile transmission, and are thus treated with a protective corrosion resistant coating. Formed sheet spring steel retainers tend to abrade the surfaces of the tubular conduit and housing portions of the coupling which are in contact with the outer contacting portions of the retainer itself and thus wear through the protective coatings on those portions, especially when the coupling is used with vibrating machinery or pulsating pressures. Certain formed sheet spring steel retainers subjected to relatively high pulsating pressures have failed during use due to fatigue of the portions of the retainer which repeatedly vibrated in contact against the opposing housing portions.
In order to simplify handling of the parts of the coupling assembly of the type described, it is desirable to provide housing and conduit subassemblies wherein each subassembly is self contained and ready for connection with the other to complete the coupling. Preferably all of the components of each subassembly comprise a unitary assembly suitable for shipping (without loose components requiring separate handling or subject to possible loss) to the location where desired for connection with the other subassembly. Although it has been conventional to provide the conduit, seal, and retainer as a shippable conduit subassembly ready for connection with a housing subassembly, certain conduit subassemblies have not been considered to be satisfactory in that they were open at the entry end and subject to collecting dust, dirt or the like during transit and subject to damage during handling and shipping.
Frequently in use, the aforesaid housing is secured to a hydraulic mechanism, as for example an automotive transmission housing, prior to insertion of the tubular conduit to complete the coupling. It is then desirable to provide a perforatable diaphragm seal to close the housing passage until the aforesaid tubular conduit is inserted, whereby the leading edge of the conduit pierces the diaphragm seal and renders it operative. Perforatable diaphragm seals are well known to the art, but all such seals used heretofore are fixed deep within the housing passage. The entry opening and the enlarged diameter passage of the housing thus remain exposed to dust and incidental corrosive debris which is subsequently carried into the hydraulic mechanism during operation, resulting in damage and excessive abrasive wearing of the mechanism. Heretofore, no one has provided suitable means for closing the entry to the housing passage prior to completion of the coupling by insertion of the conduit.